924Board.org

[ryson]

i just dont want to spend 200 dollars worth of fuel pump and the engine still didnt work, my friend told me its a fuel pump and he is just guessing it. the engine does start but it wont hold idle stage, it die shortly.
the engine seem to stutter and crank alot. help me pls
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1977 porsche 924
1978 porsche 924
1983 porsche 944

[CBass]

Start the engine and try holding the throttle open. If the engine runs with the throttle opened up, then the fuel pump is not the cause. If cuts out from lack of fuel while holding the throttle open, try first cleaning the contacts for the fuel pump, and the contacts where the relay is at the fuse box. Use jumper wires to replace the relay, to make sure that it isn't the problem.

Check the ignition system first make sure your plugs are clean, the wires aren't in poor repair, that the cap and rotor are still good. Check that the ignition timing is still good, and hasn't come out of adjustment at all. Check that the timing belt mark and flywheel marks line up like they should.

Go over the engine with a can of quickstart and spray it anywhere that there could be a vacuum leak, using a squirt bottle of water is also good for this.

Pull out all of the fuel injectors, and stick each one in a clear bottle, one liter pop bottles work great for this. Jumper the fuel pump, remove the air intake boot over the CIS fuel distributor, and pull up the plate. The injectors should start spraying fuel into the bottles. Look at each injector and see if you're getting a good mist coming out of it, or if it's dribbling or spraying a stream. You want a nice even mist of fuel. After a checking all of the spray patterns this way, put the bottles side by side and see how even the fuel level is in each bottle. If all teh injectors are clean and working properly, it should all be the same. You might see one or two spraying too much or too little, they should be replaced or cleaned. Cleaning them involves soaking them for about a month in fuel injector cleaner and blowing them out with compressed air.

If you've verified that the ignition is functioning properly and the timing is set, that there are no major vacuum leaks, and the fuel injections system is functioning properly, then I'd start to worry.
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'81 931 in various states of assembly

[gohim]

80 and later 924 and 931 cars have two fuel pumps. If one goes bad very often the engine will not run smoothly.

Earlier cars only have one fuel pump.

Don't expect the engine to run right if you replace the wrong fuel pump.